Manufacture of pointed tubular metal articles



Dec.20, 1932. 1,891,304,

MANUFACTURE OF POINTED TUBULAR METAL ARTICLES Filed Aug. 4. 1930 Patented Dec. 20, 1932 UNITED STATES PATENT OFFICE IANUIACTURE OF POINTED TUBULAR METAL ARTICLES Application filed August 4, 1980, Serial No. 473,125, and in Great Britain-August 22, 1929;

This invention comprises improvements in the manufacture of pointed tubular metal articles and particularly hypodermic syringe needles.

According to the specification of my United States Patent No. 1,568,369, tubing for such needles is produced by reduction to small uge of a tubular billet containing a core 0 metal capable of extreme elongation and retention of tensile strength. For some purposes, steel needles with a lining of incorrodible metal are desired, and th1s was accomplished by enclosing the core in a tube of lining metal before inserting it into the tubular billet. After rollin swaging or drawing the composite billet own to the required tube gauge, the tube was subjected to heat treatment, for annealing the core, the rolling, swaging or drawing operation and the heat treatment causing the lining to be welded, soldered, or intimately allied with the interior of the steel tube;

According to the present invention the cored tube is'subjected to a heat treatment or heat treatments so controlled as to anneal the core and tem r the tube whilst on the core. Thus with w ll; of certain alloys which are used in the hard drawn state, the heating of the composite wire, is controlled so that a softening or annealing of the core and a temperin of the tube is effected but is stop ed ort at the point at which the tube itsel is correctly tem red. Or where the composite wire 1s heated to a temperature suflicient for causing a lining to be united or welded to the inside of the tube and for softening or annealing the cone, the heat treatment is followed by a uenching and reheating, for the purpose 0 hardening and tempering the tube metal, whilst the tube is on the core. The grinding and finishing of the needle point are advantageously performed whilst the tube is still on the core. In this way the point may be produced without the disadvantageous burr which results when the point is produced after the removal of the tube from the core. The polishing, cutting of a screw thread, and the lglating of the exterior of the tube may a o-be performed whilst the tube is on the core.

In the drawing, illustrating one suitable method for carrying out the invention; I

Fig. 1 is a longitudinal section of a core, lining metal and a tubular billet;

Fig. 2 is an enlarged view of a finished I a controlled heat treatment or treatments as will be hereinafter described so as to anneal the core a and temper the tube 0 while the latter remains on the core. The rinding and finishing of the needle point 5 is performed while the tube still remains on the core. A cut is made at e at the exact int of division for a needle length, the tu is cracked at this point but not the core, and the tempered and finished needle is drawn off the core. l

' In carrying the invention into effect with a tube of alloy sold commercially under the registered trade-mark N ichrome and a core of brass, the heating of the heat treatment is carried up to 620'degrees centigrade for two minutes and is then terminated. The brass core is softened or annealed by this treatment and the nickel chrome alloy of the tube is tempered but otherwise remains unaffected.

patent aforesaid, and the tube is tempered and remains in the tempered condition.

With tubes of carbon steel an incorrodible metal lining may be united to the tubes. The core is enclosed in the metal lining before inserting it into the tube. The lining is partly allied or welded with the tube by the working of the composite wire and by the flux or solder which may have been interposed. The comosite wire is then heated to about 950 C. or annealing the core and for completing the alliance of t e lining to the outer tube. The composite wire is then reheated to about 780 C. and quenched to harden the outer tube.

Finally, the composite wire is reheated to about 300 C. for the purpose of tempering the tube metal and the core is removable as described in the specification of my prior atent aforesaid, after being pointed and po ished.

' With tubes of Firths steel sold commercial- 1 under the registered trade-mark F. H. teel, the composite wire is heated to between 850 C. to 1050 C. for annealing the core and tempering the outer tube. This variation in P the tempering temperature may actually be encountered in practice. It may be possible to accomplish the heating in one operation. Thus the composite wire may be heated to a temperature between 850 C. and 1050 C. and the rate of cooling adjusted to the temperature selected. The temperature selected may be 950 C. with an oil quench or 1000 C. with air cooling or 900 C. with a. water uench. The lower the temperature selected, t e faster-working must be the quench, and

the above temperatures must only be taken as approximate as they may vary with a particular set of circumstances, but the principle remains the same.

The core or mandril metal may be selected for its expansion characteristics and so that the expansion of the core metal during the heat treatment is greater than the expansion of the tube metal. This expansion further Biomotes the welding or closer alliance of the ing metal with the tube metal and facilitates the ultimate separation of the tube lengths or needles from the core when cold. This latter effect is obtained, of course, with equal advantage when the linin is dispensed with, as when certain hard al oys are used for making the needles. For example, an alloy containing nickel, iron, chromium, molybdenum and tungsten (known as contracid) may be subjected to a heat treatment at a low temperature of 600 C. to 720 C. This treatment, whilst annealing the core and tempering the tube produces such a degree of expansion of the core, which may be of nickelsilver or brass that the contraction of the core when cooled, facilitates the separation of the tube from the core. This heat treatment can be successfully adapted to any steel or alloy which work-hardens, but which tempers and does not fully soften by a heat treatment at a tem erature below 750 C. High .carbon stee s with or without other alloying elements, and steels such as stainless steels of varying composition may also be subjected to a similar heat treatment.

The grinding of points on the tube lengths in the production of the finished needles is frequently a dilficult and troublesome operation, particularly in the case of lined stainless steel needles and certain others, notably nickel alloy needles. The reason for this is that a burr is formed within the point and as the presence of such burr is hi hly objectionable and even dangerous, it is important that it should be removed so that the finished needle shall have a perfectly clean point. These improvements avoid the diificulty and the defects above noted and effct an important economy bly producing a finished cannula needle wh' st still on the core. Thus, when the composite billet has been reduced to the approprlate gauge and the needle lengths or double needle lengths have been produced, the oint or points is or are formed, as b grindmg, whilst the bore is still occupied by the core.- In this way a perfect point is produced containing no dangerous burr. Furthermore, there is the assurance that such a point can contain no foreign matter such as grinding swarf, dirt, or unsterilized matter. This is also very important in the polishing because a very much cheaper method known as scouring can be adopted without danger of spoiling the needles through filling up the bore. In practice, when the tube and core have been reduced to the proper auge, and the heat treatment has been er ormed, the exterior is polished, the point 1s ground, any necessary screw thread is cut and the tube may be plated with nickel for example, whilst the tube is on the core. A cut is marked at the exact point of division for a needle length, the tube is cracked at the said point but not the core and the finished needle is drawn off the core. Naturally, the method is applicable whether a single needle is produced each time, or whether a double needle length is produced and two finished needles are pulled from ofl the single core length.

1. In the manufacture of hypodermic syringe needles, reducing to a small gauge a composite wire comprising a hard metal outer tube containing a core of metal capable of extreme elongation and retention of tensile strength, heating said wire to a temperature suflicient for annealing the core, controlling such heat so as-to temper the tube whilst the tube remains on the core, grinding and finishtube and withdrawing the tempered and finished needle length from the core.

2. In the manufacture of pointed tubular metal articles such as hypodermic syringe needles, reducing to. a small gauge a composite wire comprising a hard metal outer tube, an incorrodible metal lining for said tube and a core of metal capable of extreme elongation and retention of tensile strength, 1 heating the composite wire to a temperature suflicient for softening the core and for uniting the lining to the tube, quenching the composite Wire to harden the tube, and reheating the composite wire to temper the tube metal and withdrawing the tempered tube from the annealed core.

3. In the manufacture of pointed tubular metal articles such as hypodermic syringe needles, reducing to a small gauge a composite wire comprising a hard metal tube, an incorrodible metal lining for said tube and a core of metal capable of extreme elongation and retention of tensile strength, heating the composite wire, controlling such heating so as to anneal the core and temper the tube metal whilst the tube remains'on the core, grinding and finishing a needle point on the tube whilst still on the core, severing a needle length of said tube, and withdrawing the tempered and finished needle from the annealed core.

4. In the manufacture of hypodermic syringe needles, reducing to a small gauge a composite wire comprising a hard metal outer tube containing a core of metal capable of extreme elongation and retention of tensile strength, heating the composite wire, controlling such heating so as to anneal the core and temper the tube metal whilst the tube remains on the core, grinding and finishing a needle point on the tube and polishing the exterior of the tube whilst said tube is still on the core, severing a needle length of said tube, and withdrawing the tempered and finished needle from the annealed core.

5. In the manufacture of hypodermic syr inge needles, reducing to a small gauge a composite wire comprising a hard metal outer tube, a metal lining for said tube, and a core of metal capable of extreme elongation and retention of tensile strength, heating the composite wire to a temperature suflicient for softening the core and for uniting the tube to said lining, quenching the composite wire to harden the tube, reheating the composite wire to the tempering temperature of the tube metal, grinding and finishing a needle point on the tube whilst said tube remains on the core, severing a needle length of said tube,

and withdrawing the tempered and finished needle length from the annealed core.

ing a core of metal capable of extreme elongation and retention of tensile strength, heating said wire to a temperature sufiicient for annealing the core, controlling such heating so as to temper the tube whilst the tube remains on the core, polishing and screwthreading the tube whilst 'still on the core, severing a length of such tube and withdrawing the severed length as a finished article from the core.

7. In the manufacture of tubular metal articles such as hypodermic syringe needles, reducing to a small gauge a composite wire comprising a hard meta-l outer tube containing a core of metal capable of extreme elongation and retention of tensile strength, heating said wire to a temperature sufficient for annealing the core, controlling such heating so as to temper the tube whilst the tube remains on the core, polishing, screw-threading and plating the tube whilst still on the core, severing a length of such tube and withdrawing the severed length as a finished article from the core. 7

SAMUEL J. EVERETT.

6. In the manufacture of tubular metal articles such as hypodermic syringe needles, reducing to a. small gauge a com ite wire comprising a hard metal outer tu contain- 

